This application relates to improvements in capacity control systems for scroll compressors.
Modern compression applications often utilize scroll compressors. Scroll compressors comprise an orbiting scroll which has a base and a generally spiral wrap extending from the base. A non-orbiting scroll also includes a base and a generally spiral wrap which interfits with the spiral wrap of the orbiting scroll. A number of compression chambers are formed between the two wraps. The orbiting scroll is driven by an electric motor to orbit relative to the non-orbiting scroll, the volume of the chambers is reduced, and an entrapped fluid is compressed. There are usually a pair of associated chambers being compressed towards a discharge port.
In some applications, it is desirable to reduce the compressed fluid volume. In the prior art, vent ports have typically been formed through the base of the non-orbiting scroll, with a port associated with each of the pair of scroll chambers. Thus, there have typically been at least two vent ports for allowing fluid to flow out of the compression chambers.
In the prior art, complex valving structures are incorporated to open and close the ports. Further, there has typically been separate valves associated with the two vents. Also, the prior art has typically utilized electronic valves associated with each of the ports.
The use of the two separate valves is somewhat undesirable in that the actuation has not always been synchronized. This may result in unwanted noise, vibration, etc. Further, the use of the separate electrical valves increases the cost and complexity of the scroll compressor.